Channel selector



Sept.- 12, 1950 D. R.' D TAR ETAL CHANNEL; sELEr'zToR s sheets-sheet 1 Fiied Feb; 24, 1949 Sept; l2, 1950 D. R. DE TAR ET Al. 2,521,958

CHANNEL SELECTOR i Filed Feb. 24, -1949 3 Sheets-Sheet 22y Sept. 1.2,.1950

D. R. DE TAR ET AL 2,521,968 v CHANNEL SELECTOR Filed Feb..` 24, 1949 s sheets-sheet s v 70 [if A25 @ffm Patented Sept. 12, 195o UNITED STATES PATENT OFFICE CHANNEL SELECTOR Donald R. De Tar, Stratford, Conn., and Martin J. Kirk, Chicago, Ill., assignors to Aladdin Industries, Incorporated, Chicago, Ill., a corpora'- tion of Illinois Application February 24, 1949, Serial No. 78,214

(Cl. 25d-40) 11 Claims.

Our invention relates to an improved channel selector particularly suitable for use in television receivers.

In television receivers it is necessary to provide tuning means selectively adjustable to any one of many television station channels. These channels currently cover two separate and disany other channel in the most convenient direction, whether backward or forward.

In addition to the foregoing considerations it is desirable in a tuner for television purposes to provide means operable to tune very closely to the selected channel and vernier means adjustable to center the tuner precisely on the desired frequency. The former means adjusts the tuner sufdciently close to the channel to provide a view of the image and some response to its audible accompaniment. The latter means permits adjustment to minimum distortion, particularly of the audible accompaniment to the visual.` .program.

Further it is desirable to provide a tuner suitable for television purposes which is precise and at the same time demands a minimum degree of machining and other expensive production processes. In accordance with the present invention this desirable attribute is achieved by providing elements individually adjustable to center the frequency to tuning on the desired station channel and means to utilize the effective tuning movement to cover two frequency ranges in a mechanism otherwise capable of covering only a single tuning range.

Apparatus shown herein but not claimed is shown and claimed in the copending application of Donald R. De Tar, entitled Tuning System, S. N. 78,213, assigned to the same assignee as the present invention.

It is therefore a general object of the present invention to provide an improved channel selector suitable for television purposes.

A more specific object of the present invention is toprovide an improvedchannel selector capa"v ble yof adjustment to any one of a group of fre quency channels and movable in either direction y from one channel to another.

Another object of the present invention is to provide an improved channel selector capable of covering frequency channels in two bands spaced apart by a substantial frequency.

Still another object of the present invention is to provide an improved channel selector capable of covering frequency channels in two bands and which permits use of one kind of tuner in one band and another kind of tuner in another band.

Yet another object of the present invention is to provide an improved channel selector capable of adjustment to any one of a plurality of predetermined frequencies and which at the same time involves no precision machining.

Further it is an object of the present inventionv to provide an improved channel selectory having Vernier means to adjust the tuning pre-y cisely to the desired frequency.

It is still another object of the present invention to provide an improved channel selector having individually adjustable elements to set the tuner at any one frequency channel and in which the elements may be set only when the i the center of its range ofy Vernier means is in movement. Y

The novel features which we believe to be chari reference to the following description .taken in f connection with the accompanying drawings, in which:

Figure 1 is a View in perspective oi a tuner constructed in accordance with the principles of the present invention but with the individual inductors removed;

Figure 2 is a top plan view of the tuner of Figure 1 and showing the tuning inductors in place;

Figure 3 is a side elevational view of the tuner of Figure 1 and showing the tuning inductors in place;

Figure 4 is a front elevational view of the tuner with the tuning knobs removed;

Figure 5 is a cross sectional view through axis 5 5, Figure 4;

Figure 6 is a cross sectional view through axis 6 6, Figure 2;

Figure 7- is a cross sectional view through axis 1-l, Figure 6;

Figure 8 is a diagrammatic view showing the switchmechanism .ofthe structure of Figure 1;

is used to refer to the mechanism by which one,r

or more tuning members are moved to tune to one or more station channels or frequencies;

The term tuner is used broadly to refer to accordance with the movement of a tuning member. In the specific device described herein the 4 port 32 to form a unitary structure of screw, support, and-core or sleeve.

Each screw S has a screw driver receiving slot Sli-o., Figure 2, for the purposes of adjustment. The carriage 38 has an array of openings Sa, Figure 6, in alignment with the inductor 24.,and36 and eachbadaptedrto threadedly receive; afscvewst,y l i ff I' f' The carriage 36 is held for shifting movements on the track defined by rails 22S and 38. These rails are each amxed at one end to the back plateii 'and at the opposite end to the front kvplate 36'. y The carriage 3G has an opening which tuner is an inductor having its indu-stance varied by movement of a tuning member comprising` a.

magnetic core or a conducting sleeve.

Referring now to Figuresl t ,3,: the channel selector .comprises a back.l plate 2n capable vof receiving an upper mounting memberY 22 Whichin `turn supports a group-of core type tuning inductors al V(Figures 2 and 3). The back plate El also receives a lower mounting member 2G to which is affixed a plurality of corresponding sleeve type tuning inductor-s 28 (Figure 3).

Each core type tuning inductor 24 has a cooperating shiftable magnetic plunger 2 4a capable of varying the inductance thereof and hence the frequency of tuning, When these cores are in thev inserted position, where they are almost wholly within the hollow inductor portions 24 of the inductor, the inductance is at the maximum value and the resonant frequency corresponds to the lowest channel of the low frequency television band,` namely, about 57 megacycles. Vihen these cores are withdrawn from the inductor portions, the inductance is de creased and the resonant frequency rises to va value corresponding to the highest channel` of the low .frequency television band, namely; about 85 megacycles.

Each vof the sleeve type tuning inductors 28 has a cooperating tuning sleeve 28a adapted-to fit into the annular space between each.- inductor-v and the corresponding magnetic core 28h. ThisA sleeve is made of aluminum or like conducting material and is capablelof being inserted into or f' withdrawn from the corresponding inductor by movement in the same.` direction as thermovement ofv cores 24a. As these sleeves areinserted,

into the inductors, they act as short .circ.uited, low impedance turns havingY increased degrees of coupling with the inductor and, increased shielding eifect on cores 28h, thereby increasing the resonant frequency of. the circuit of which each inductor forms a part. V'lhe inductors 2i!` and sleeves 2da are designed to tune theV circuits with Whichthey are associated to the lowest. channel of the high frequency televisionband (about l'l'megacycles) when withdrawn andto the highest channel ofthe high frequency television band (about 213 megacycles) when com.- pletely inserted` The cores Ella and thelsleeves ZBaaresupported for movements in unisonr'by the vshiftable carriage 38. This support is derived from a plurality. of flexible wire supports one connected to each of the sleeves and cores, and each carrying at its opposite end the externally threadedscrew 34;k

The carriage 3D receives the screw: 34 corresponding to each support 32,. Each of these screws is attached.to..the.correspondingsup.

receives bushing 4S which in turn receives the 1'a1;38,asshown in Figure 6. The carriage 3d also defines ay hook shaped portion 30h which nearly encircles rail 3G as also shown in that figure. vThus 'carriage 3l) is restrained for shiftingA movements in the direction or orientation of the rails 38 and Si? and hence the direction of forientation L of the y inductgrs 2li .and ,28.

A centrallyl dlsposedgfsnaft i2 extends from. back plate 2id to front plate 46 below and,l intermediateqrailsfvli and 3S.; 'lhisshaft is aligned with these railsfand receivesia cam assembly indicated;'generallygat 44., Y

The assemblylllhi isfslidably. received on:

shaftgd L.but-is held for rotationstherewith. This.l

is -accompiishedgby the .,keyway 42a extending along the length fof shaft and which receives thergrnating:lieyportioniof:'camfil as seen best l in Figure 1l. n y The icamrassembly lfdeines a cam gyformed blvget radially :extending wing.Jv This wingA curves as it encirclesltheshajft i2 to deiineacontinuousq surface l. having diametrically `opposed Y portions. ittici and Figure 2,..at`the extreme axialpo or a molded phenolic;material;`

The carriage. 36 is lheld for shifting movements in .response/to rotation of camzM byhthespring biased-talsecupseenfbest in thegview of Figure 7. A, Y This.V devicegis affixed:l to the bushing i3 whichrv is mounted cn. carriagex and denesa passage to receivathe` rail. 138. Rearivardlyiof thelcar` riagev Sr; the-bushing Lisi-receives pair of V-spacedl l diskssi'l. andI 521i which havetaligned; openings to receive etica: detent 54. The ylatter A 'm,enaecnv has :Y *fr anlannularLwall 5ta.,A against which-1coil spring.'

55 lbottomsto urgethe;.detent against thezsur-f face E of the cam.

The carriage 30 lextends toranfaligried position mountaintherein:j,l

Under the: biasy of springv @datent-574; isurg'edl, against the cam surfacefib to-hold button .58;1

snugly against; cam-'surface Minn Carriage 13u: is

` thereby .Veenstra-ined; to'v4 shift; in; response;r to the. f

axial positioning-,of'theiparticular portion of camI surface ,d sandwiched between fbuttonf. 58 and de-.f -A

tent 54A# As seenzbestfin thecr'ossssectional view of Fig-f 2: ,ure 5, the cam 44 is urged backwardly*towards'A the back; plate 2li byu-the; spring :This spring.`

bottomsagainstftheituireiz plate flwhichisheld tivetdiplatezfribyzthe annular Wall i'a'- and the snap ring ll, thefrlatterf.beingwireceived incarico-1re? operating circumferential groove in.l sleeve 166."

aba-uses.;

cmferentially spacedadjusting' `screws 12,- v one l corresponding to keach of the stationchannels desired to be tuned. Each, ,of .these screwsdsl threadedlyreceved on turret plate .62 and has a `Slt12a adapted to receive a4 screwfV driver for shifting ymovements in adirection parallel to shaft 42.

The stop 14 hasa V-shaped portion 14h with l 'bottom against. the.4

' ing movementsy relative to back plate 2t byk pinannular wall 80a and thecooperating snap ring 82, the latter being received in a suitable circumferential slot formed in sleeve' 80.

The bushing 80 also receives the disk 84 which is fixedly attached thereto andv rotates with the rotations of the sleeve. This disk is in frictional engagement with the opposed resilient disks l86 mounted on sleeve 66 and which snugly receive disk 84 near its outer periphery;

`The'bushing 66 extends outside theV front plate 40,A Figure 1, and there receives the Vernier tuning knob 88 as shown. When'this knob is rotated, disks 86 and 84 are likewise rotated. This varies thethreaded engagement between sleeve 80 and stud 78 to shift stop 14 relative to front platev 4D. As a' consequence, the entire cam 44' is bodily shifted and the'position ofcarriage 30 altered accordingly. y

will be described in further detail hereafter, the cam surface 46 is shaped to shift carriage 30 tofpositions roughly corresponding to the positionsv requisite for the desired tuning. At each station point or channel, the carriage is accurately adjusted to the desired position by adjusting the position of the corresponding screw 12, thus compensating for deviations in the shape of cam surface 46 from the surface necessary to achieve perfect tuning. Vernier adjustments at any one channel are achieved by rotation of bushings 66 to overcome any inaccuracies in the settings of.- screws T2 and theeffects of variations of temperature, humidity, etc. on the tuning.

The 'cam 44 is provided with a cam surface 48 n defining a continuous surface with diametrically opposed points 46a and 46o, Figure 5at opposite extremes of axial position. Consequently, as the shaft 42 is. rotated over a 4full revolution -(360), thefcarriage 30 is first shifted from one extreme axial position to the other extremeaxial position and then shifted back to the initial position. In .accordance with the present invention switch elements are correlated With these shifting movements to connect the core tuned inductors 24 in circuit during` the first movement and the sleeve tuned inductors 28,in circuit during the second movement.

The switch structure may best be understood by reference 11o-Figure 10 which is a cross-sectional 1 viewthroughFigure 3 'and showing the switch operating elements.

ed on shaft 42 adjacent backplate 20. .This disk has acontinuous groove |0011. cut in its back face to denea. cam groove to receive the roller |02a of yrockable arm |82. The latter is held forrock- |02b shown incross section in Figure 10.'l

The arm |02 has a forked end portion I02c which receives the pin |04'a mounted on crank arm |04. The latter is rockably lsupported from ATheswitclrrail |06 is held for shifting movementsrelative to back plate 20 by forwardly bent portion 20a, 'Figure 3, of that plate which cooperates with lower mounting member 26 to define a slot to receive that rail. The rail |06 is guided within the slot so delined by the pins |08 Awhich extend from portion 20a of plate 20 to points adjacent member 26. i

The rail` |06 is of insulating material, such as a phenol formaldehyde condensation fproduct, and is formed with a plurality of spaced conducting inserts lila, one corresponding to each pair of inductors. is of similar insulating material having a plurality of spaced contact buttonsk 22a, Figure 10, one corresponding to each core tuned inductor 24 and connected thereto as shown in Figure 8.

The lower mounting member 26 has a plurality of forwardly facing contact buttons 28a, Figure 1'0, adaptedl to engage the rail |06 when it is shifted to the left hand extreme of movement as seen in Figure 10. These are shown in cross section in Figure l0 since they protrude from member 26y into the plane of the cross section of that figure. As shown in Figure 8, each of these contacts is connected to one of the sleeve tuned inductors 28.

The member 26 further has a plurality of spaced contact buttons 2Gb. These are like buttons 26a but are positioned intermediate buttons 22a and 26a for continuous contact Awith the conducting members |06a. As is shown diagrammatically in Figure 8, these contact buttons are connected to the several circuits desired to be tuned such as, for example, the lirstand' second lf radio frequency amplifiers, the mixer, and the i local oscillator vof a superheterodyne` television receiver.

It will be'ob'served that the groove |06a is at* f a small radial distance from rshaft 42 over substantiallyhalf of vits circumferential length and at a larger radial distance for substantially the .c5 remainder of its length. Consequently, as the shaft 42 is rotated arm |02 hasthe position of Figure 10 for half the revolution andis rocked. in the clockwise direction for the remainderof the revolution. When the arm |02 is in the position of Figurek 10 the shiftable rail |86 is in the right hand extreme of movement as seen in is in the other extreme of movement as shown in the dotted lines of Figure 10, the shiftable rail |02 is shifted to the left hand extreme of movement as seen in Figures 8 and 10 and connects the. sleeve tuned inductors 28 in the circuits by greason ofithe contact established between conf As shown, a disk |00 ismount- The upper mounting member 22'-y 7 tact `lmitinm` 266 and ualby the conductingmembers 186e.

The rocking movements oiarm 102. are cor related with the shifting morementsof carriage. 36 to cause the inductors 24 to be connected to. the circuits when cam 44 shifts carriage 3U inone direction with .clockwise rotation of shaft. vand to connect inductors 24 in .the circuits whenfcam 44 shifts carriage 3D in the Opposite direction with clockwise rotation .of shaft 42.

Thus as the shaft 42 is rotated over a complete revolution A(360) starting with one o i thediametrically opposed extreme points (45a ,or 4Gb) in registry vwith Vfollower 154, the following eventsl take place:

A. Low band channel selection (channels 2 to 6):

l. Over the first half revolution tol80) the core tuned incluctors 24 are connected in circuit.

The carriage 3 progressively withdraws the cores 24a and sleeves 28a from the inductors.

The inductors 2t are tuned in steps from one channel to another in order of increasing frequency.

B. Switch actuations:

one channel to another in order of increasing frequency.

D. S=witch actuation:

8. Shifting of rail HIS disconnects inductors 2.8 and connects inductors 24.

It will be observeclthat rthe total shifting movement of carriage 3l) eiective for tuning is twice the actual distance between the extremes of carriage movement. This is accomplished by causing the withdrawing movement to cover one tuning band and the inserting movement to cover another tuning band.

Moreover, the segregation of the two tuning functions, one corresponding to each band, permits use of one type tuner in one band and another type tuner in the other band. This has the advantage of permitting optimum design of each tuner as dictated by the tuning range desired to bey covered.

The star wheel 64, Figure 9, and the detent arm H0 coact to impart snap action to the rotational movements-of the shaft 42 and to register one of the screws 'l2 with the stop 14 at all times. The arm l I- has a roller I ma which rides on` the periphery of wheel 64 and is biased against that wheel by the spring l I2.

Star wheel 64 has a plurality of spaced openings 6411, one corresponding to each of the screws 12. These are in registry with these screws to permit xaccess to the same :from `front .panel 4.0.

Front panel 4B has `an opening 4ta, Figure. 9, in registry with the ,stop 14 and .hencethe par-y ticular screw 12 bearinglagainst that atop;V Howd ever, accessto this screw from front paneill is i normally yobstnsicted Vby disk 84.

positionedto register with opening 40a oniy when disk .84'15 in the position half way between the extremesof movement thereof.

lWhen the opening; 84a .is registered with they opening 4a.the Vernier -adiustment'of the tunai is in the intermediate position and capable Aolv equal adjustment in .either direction. By adjust-- ing the specic screw 12 in rregistry with thest .L 14 to center the channel being tuned to the riei sired ffrequency'while .the Vernier is in this intermediate position, amaximum degree of for intureadjustment by Vernier action is assured;

While we have shown and describedonr inven- .tion as applied to a structure -wherein half ri.

the channels are in one frequency band .and the other half are in another frequency band, it wiii be observed that byproperlyforming cam 416 the groove Hwa in disk 100, the unit may be. operated over frequency bands hav-ing unequal.` Moreover, by appropriate;

numbers of channels. design of cam the station channels maybe equally spaced insofar as rotation of shaft 42' is concerned even'though their frequency spacngs are unequal andtherequired movements of carriage 30 are not equal.

While it is preferable to use sleeve tuners and l core tuners in combination to enable mounting.v Ona common support,V it is possible to provide auf arrayv of tuners of one .type or the other arranged facing each other so that movement of the carriage withdraws the core or sleeve of 4one` tuner'of each pair and inserts the core or sleeve of the other tuner of each pair.

In Figure 8, the tuners 24 and 28 are .eachshown as an inductor with a shunting capacitor.-

The latter represents the inherent distributed capacitance of the inductor and ,any separatef.

lumped capacitance provided.

While we have shown and .described a specific embodiment ofour invention it .will of course be understood that we donot wish to be limited':

thereto and that by the appended claims we intend to cover' all modifications and alternative constructions as kfail within the true spirit .and scope of our invention.

What we claim as new and desire to secureI byLetters Patent ofthe United States ist said carriage to impartv Atuning movement to said member, a cam defini-ng a` surface variably posi;

tioned in the direction of said movement, means connecting said carriage to said cam to follow said surface as -saidcam is rotated, means biasing` said cam to urge said cam and said carriageV toward one extreme of movement of said meme ber, a stop adapted torestrain movement of said cam in response to said biasing means, and lndi.

vidually adjustable elements-mounted for rota-l" tion vwith said cam and individually -operable to` engage said lstop in accordv with the rotations vof said cam.

2. A .channel selector'ior use with a tuner having a member movable to accomplish tuning:v

action, said selector comprising a carriage .sup-

porting Vsaid member,y means movably supporting., said carriagem impart :tuning movements 'to said" lmember, al cam defining a surface variably posi- "tioned in the vdirection of said movement, said surface Ibeing ,oriented generally transverse .to

.said direction, meansv on said carriage adapted *to restrain said carriage to follow said surface as said cam isrotated, means biasing said'cam to urge said cam and said carriage toward one extreme of movement of said member, a stop adapted to restrain movement of said cam in response to said biasing means, and individually adjustable elements mounted for rotation with said cam and individuallyA operable to engage said stop in accord with th'e rotations of said cam.

*3; A channel selector for use with a tuner having a member movable to accomplish tuning action, said-selector comprising a carriage supportingsaid member, means movably supporting said carriage to impart tuning movements to said member, a cam dening a surface variably positioned in the direction of said movement, means connecting said carriage to said cam to follow said surface as said cam is rotated, means biasing said cam to urge said cam and said carriage toward one extreme of movement of said member, a stop adapted to restrain movement of said cam in response to said biasing means, individually adjustable elements mounted for rotation with said cam and individually operable to engage said stop in accord with the rotation of said cam, and means adjustably supporting said .stop for varying the position of said stop at any position of said cam without altering the corresponding adjustable element.

4. A channel selector for use with a tuner having a member movable to accomplish tuning action, said selector comprising a carriage supporting said member, means movably supporting said carriage to impart tuning movements to said member, a cam dening a surface variably positioned in the direction of said movement, a shaft adapted to rotate said cam, means connecting said carriage to said cam to follow said surface as said cam is rotated, means biasing said cam to urge said cam and said carriage toward one extreme of movement of said member, a stop adapted to restrain movement of said cam in response to said biasing means, individually7 adjustable elements mounted for rotation with said cam and individually operable to engage said stop in accord with the rotations of said cam, and shaft means coaxial with said rst shaft adapted when rotated to shift the position of said stop in the direction of movement of said member.

5. In a channel selector of the type wherein a tuning member is moved in response to a cam defining a surface variably positioned along its axis of rotation, the improvement which comprises means biasing said cam in one direction along said axis, a stop adapted to restrain movement of said lcam in response to said means, and individually adjustable elements mounted on said cam for rotation therewith and individually adapted to engage said stop as said cam is rotated, thereby to move said tuning member in response to the configuration of said cam and the adjustment of said elements.

6. In a channel selector of the type wherein a. tuning member is moved in response to a cam deiining a surface variably positioned along its axis of rotation, the improvement which comprises means biasing said cam in one direction along its axis, a stop adapted to restrain movement of said cam in response to said means, individually adjustable elements mounted on said 10 cam for rotation therewith and' individually adapted to engage said stop `as said cam is rotated, thereby to move said tuning member in response to the configuration of said caml and the adjustment of said elements, and means t0 shift the position of said stop in said direction for further adjustments of the position ofL said member at any one cam position. f.

7. In a channel selector of the type wherein Aa tuning member is moved in response toa cam defining a surface Variably positioned along its axis of rotation roughly in correspondence with a plurality of preselected tuning positions of vsaid member, the improvement which comprises means biasing said cam in one direction alongits y 4,tion therewith adaptedindividually to engage said stop as said cam vis rotated to the positions correspending to said tuning positions, whereby discrepancies in the tuning due to the deviations in the shape of said cam from the intended shape or to deviations in the frequency characteristics of the tuning members may be compensated by adjustments of said elements.

8. In a channel selector of the type wherein a tuning member is moved in response to a cam defining a surface variably positioned along its axis of rotation roughly in correspondence with a plurality of preselected tuning positions of said member, the limprovement which comprises means biasing said cam in one direction along said axis, a stop adapted to restrain movement of said cam in response to said means, individually adjustable elements mounted on said cam for rotation therewith adapted individually to engage said stop as said cam is rotated to the position corresponding to one of said positions, whereby discrepancies in the tuning due to deviations in the shape of said cam from the intended shape or in the intended frequency characteristic of the tuning member may be compensated by adjustment of said elements, and means to adjust the position of said stop over a limited range to compensate for frequency drift or for errors in the settings of said elements.

9, In a channel selector of the type wherein a turret bearing an array of adjusting elements is rotated to preselected positions corresponding to as many tuning positions, and in each position one element registers with means to fix the frequency of tuning, said selector having vernier adjusting means operable to compensate for frequency drift or for errors in the settings of said elements, the improvement which comprises a disk adapted to overlay said one adjusting element and having an opening in registry with said element when said Vernier adjusting means is substantially midway between its extremes of adjustment.

10. In a channel selector of the type wherein a turret bearing an array of adjusting elements is rotated to preselected positions corresponding to i as many tuning positions and in each position one element registers with means to x the frequency of tuning, said selector having Vernier adjusting means operable to compensate for frequency drift or for errors in the settings of said elements, the improvement which comprises a xed member extending in front of said turret and overlaying said elements to prevent access thereto, said member having an opening in registry with said one element thereby to permit access to said one element, and a disk adapted Ato overlay said opening and having an opening in registry with said first openingV when said Vernier adjusting means is substantially midway dividual-ly adjustable means sustaining each of said sleeves and said cores on said carriage, a

lmember defining a cam surface of variable axial position when traversed, means on said carriage adapted to engage said cam to cause said carriage :to follow the movements thereof, an array of individually adjustable elements associated with said cam, means adapted to hold said cam in fixed axial position in accord With the adjustment of the one of said elements in a preselected position, Vernier means operable to shiftthe posi? tion of. said cam for `precise tuning movements and switch means operable to connect the inductor of veach pair having. a. tuning sleeve to .the corresponding.. circuit whensaid camisfrotated yover one partv of its rotation and the inductor of each pair having a tuning core .to the corresponding. circuit when said. means is rotated over the other part oi its rotation.

DONALD R. DE TAR. MARTIN J. KIRK.

REFERENCES CITED The following references are of record in the i file of this patent:

UNITED STATES PATENTS Name Date White May '1, 19.46

Number 

